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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A reconfigurable AGV with omni-directional sensing

Kotze, B., Jordaan, G.D., Vermaak, H. January 2010 (has links)
Published Article / Automatic guided vehicles are being used increasingly in a manufacturing environment. Developing a platform that could be easily reconfigured is perhaps a desirable option for a user with low capacity outputs. The research described in this article concentrates on such a vehicle and the development of the actuators and sensors for navigation and proper functionality.
2

Stämmer ischemidrabbat koronarartärsområde visat med myokardscintigrafi överens med koronarartärsmorfologi visat med koronarangiografi

Bartoli, Carl, Nordlöf, Magnus January 2018 (has links)
Myocardial Perfusion Imaging (MPI) and Coronary Angiography (CA) are two methods that can be used in the investigation of ischemic heart disease. The purpose of this study is to compare medical answers from MPI and CA to find out if suspected coronary artery disease shown with MPI correlates with coronary artery morphology shown with CA, and which treatment is given based on Summed Difference Percent (SD%). The study population consists of 45 patients. The information has been retrieved retrospectively at Länssjukhuset Ryhov. Included patients had coronary heart disease accessible for percutan coronary intervention. Out of the total data sample the results show an occurring difference when it comes to medical answers from MPI and CA. The results show that most of the study participants with SD% <10 obtained solely drug treatment. Those with SD% >10 were given treatments not always according to guidelines. Elements that might have had an impact on the result is discussed. In conclusion, it appears that there is a difference in some medical answers which may be a caused of collateral circulation which causes the wrong coronary artery area to be determined as ischemic based on the MPI or because of a misinterpretation of an exam.
3

Vibration diagnosis of blades of rotating machines

Gubran, Ahmed January 2015 (has links)
Rotating blades are considered to be the one of the most common cause of failures in rotating machinery. Blade failure modes normally occur as a result of cracks due to unexpected operating conditions, which are normally caused by accidents of foreign objects damage, high cycle fatigue, blade rubbing, blade root looseness, and degradation from erosion and corrosion. Thus, detection of blade faults has an important role in reducing blade related failures and allowing repairs to be scheduled for the machinery. This in turn will lead to reduction in maintenance costs and thus raise productivity and safety aspects of operation. To maintain vital components of rotating machines, such as blades, shafts, bearings and gear boxes, at optimal levels, detection of failures in such components is important, because this will prevent any serious damage that could affect performance. This research study involves laboratory tests on a small rig with a bladed disc rotor that applied vibration measurements and analysis for blade fault detection. Three measurements: shaft torsional vibration, on-bearing vibration (OBV) and on-casing vibration (OCV), are used. A small test rig of a single stage bladed disc holding 8-blades was designed and manufactured, to carry out this research study to assess the usefulness and capability of each vibration technique in detection of incipient defects within machine blades. A series of tests was conducted on a test rig for three different cases of blade health conditions: (a) healthy blade(s) with mistuned effects, (b) blade root looseness and (c) cracks in a blade on two different blade sizes (long and short blades) in order to discover changes in blades' dynamic behaviour during the machine running-up operation. The data were collected using the three measurements during machine run-up and then recorded. The measured vibration data were analysed by computing the blades' resonance at different engine orders (EOs) related to the blade(s) resonance frequencies and their higher harmonics, to understand the blade(s) dynamics behaviour for the cases of healthy and faulty blade(s). Data have been further processed using a polar plot presentation method which provides clear results that can be used for monitoring blade integrity. To validate the obtained experimental results, a simplified mathematical model was also developed. Finally, a comparative study between three methods was undertaken to understand the relative advantages and limitations in the blade heath monitoring.

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